FIGURE 4.

Serum killing and hemolysis assay. The overnight cultures of K. pneumoniae 94 and 256 were treated with Dpo42 (A) and Dpo43 (B), respectively. The treated bacteria were immediately mixed with active or inactive serum (56°C, 30 min) at a volume ratio of 1:3, and the untreated bacteria were incubated with enzyme or active serum as a control. After 1 h incubation at 37°C, each mixture was serially diluted and plated for bacterial counting. (C) The erythrocytes were incubated with Dpo42 or Dpo43 at 37°C for 1 h with gentle shaking at 60 rpm, and the erythrocytes treated with PBS or 0.1% Triton X-100 as a control. The hemoglobin in supernatant was quantified at 540 nm. The values are indicated as means ± SD (n = 6), and the one-way ANOVA was conducted to compare multiple groups (**** P < 0.0001).